1. Field of Invention
The present invention relates in general to fuel injection type internal combustion engines and more particularly to the internal combustion engines of a type that is equipped with a variable valve control device.
2. Description of Related Art
Hitherto, various types of internal combustion engines of the above-mentioned type have been proposed and put into practical use particularly in the field of wheeled motor vehicles. Some of them are disclosed in Laid-open Japanese Patent Applications (Tokkai) 2001-221083 and 8-260923. In the publication of 2001-221083, a base operation is so made that fuel injection finishes before opening of an intake valve, and when a valve overlapping becomes to a marked value due to changing of the phase of a lift degree/working angle of an intake valve, retarding of the fuel injection timing is carried out. In the publication 8-260923, there is shown a variable valve control device that continuously varies a lift degree of each intake valve in accordance with an operation condition of an internal combustion engine.
In the internal combustion engines equipped with a variable valve control device that varies the lift degree of each intake valve, it is known that a flow speed of intake air near the intake valve greatly varies in accordance with the operation condition of the variable valve control device. That is, for example, when the valve control device provides the intake valve with a smaller lift degree, the intake air flow speed become great. However, hitherto, even by the above-mentioned publications, assured measures for controlling a fuel injection timing in accordance with the lift degree of the intake valve have been given little thought.
Accordingly, it is an object of the present invention to provide an internal combustion engine that precisely controls the fuel injection timing in accordance with a lift degree of intake valve.
According to a first aspect of the present invention, there is provided an internal combustion engine which comprises a variable valve control device that varies a lift degree of an intake valve; an air intake passage led to an intake port of the engine that is incorporated with the intake valve; a fuel injection valve arranged to inject fuel into the intake port, the fuel injection valve having a first injection mode wherein each fuel injection shot is carried out during opening period of the intake valve and a second injection mode wherein each fuel injection shot finishes prior to opening action of the intake valve; and a control unit that allows the fuel injection valve to select one of the first and second injection modes in accordance with the lift degree of intake valve effected by the variable valve control device.
According to a second aspect of the present invention, there is provided an internal combustion engine which comprises a variable valve control device including a lift degree/working angle varying mechanism that varies a lift degree/working angle of an intake valve, and a phase varying mechanism that varies an operation phase of the intake valve; an air intake passage led to an intake port of the engine that is incorporated with the intake valve; a fuel injection valve arranged to inject fuel into the intake port, the fuel injection valve being arranged to have a first injection mode wherein each fuel injection shot is entirely carried out during opening period of the intake valve and a second injection mode wherein each fuel injection shot entirely finishes prior to opening action of the intake valve; and a control unit that controls the variable valve control device and the fuel injection valve in accordance with an operation condition of the engine, the control unit allowing the fuel injection valve to select one of the first and second injection modes in accordance with the lift degree/working angle of intake valve effected by the lift degree/working angle varying mechanism.
According to a third aspect of the present invention, there is provided a method for controlling an internal combustion engine which includes a variable valve control device that varies a lift degree of an intake valve; an air intake passage led to an intake port of the engine that is incorporated with the intake valve; and a fuel injection valve arranged to inject fuel into the intake port, the fuel injection valve having a first injection mode wherein each fuel injection shot is carried out during opening period of the intake valve and a second injection mode wherein each fuel injection shot finishes prior to opening action of the intake valve. The method comprises allowing the fuel injection valve to select one of the first and second injection modes in accordance with the lift degree of intake valve effected by the variable valve control device.